Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D209/00—Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom
  • C07D209/02—Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom condensed with one carbocyclic ring
  • C07D209/52—Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom condensed with one carbocyclic ring condensed with a ring other than six-membered
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N43/00—Biocides, pest repellants or attractants, or plant growth regulators containing heterocyclic compounds
  • A01N43/34—Biocides, pest repellants or attractants, or plant growth regulators containing heterocyclic compounds having rings with one nitrogen atom as the only ring hetero atom
  • A01N43/36—Biocides, pest repellants or attractants, or plant growth regulators containing heterocyclic compounds having rings with one nitrogen atom as the only ring hetero atom five-membered rings
  • A01N43/38—Biocides, pest repellants or attractants, or plant growth regulators containing heterocyclic compounds having rings with one nitrogen atom as the only ring hetero atom five-membered rings condensed with carbocyclic rings

Definitions

• 3-Azabicyclo(3.1.0)hexane-2-carboxylic acid also known as methanoproline, and certain of its esters, are known to inhibit (suppress) pollen formation in cereal grains: U.S. Pat. No. 4,047,930 (the acid being designated therein as 2-carboxy-3,4-methanopyrrolidine).
• Methanoproline exists in the forms of two geometric (i.e., cis and trans) isomers. Each of these isomeric forms exists in the forms of optical isomers. The racemic mixtures of both of the geometric isomeric forms inhibit pollen formation in cereal grains.
• the cis racemate is more active for that purpose than is the trans racemate. Accordingly, it is desirable that there be available an effective method for preparing the cis racemate of methanoproline.
• Known methods for preparing it result in the formation of substantial amounts of the trans racemate.
• the trans racemate of methanoproline is esterified, the ester is dehydrogenated to the corresponding ester of 2-carboxy-3-azabicyclo(3.1.0)hex-2-ene, that ester is hydrogenated, and the resulting cis racemate of the ester is hydrolyzed to give the cis racemate of methanoproline.
• trans isomer is meant the geometric isomer in which the --CO 2 -- group in the 2-position of the 3-azabicyclohexane ring is trans in configuration to the bridging group in the 6-position, and the cis isomer is the geometric isomer in which the --CO 2 -- group is cis in configuration to the bridging group.
• the ester starting material can be the trans ester alone, or in any admixture with the cis ester, the product of the process provided by this invention being a mixture significantly enriched in the cis isomeric form, to the extent that in some cases the conversion is essentially complete.
• the starting ester may, for example, be an alkyl, alkenyl, alkynyl, aryl or aralkyl ester in which the ester moiety may be unsubstituted or substituted by one or more of the same or different substituents selected from halogen, alkyl and alkoxy.
• the ester is an alkyl, alkenyl or aralkyl ester in which the ester moiety is unsubstituted. More preferably, the ester is an alkyl ester having from 1 to 10, especially 1 to 4 carbon atoms in the alkyl group, or a benzyl ester.
• the ester may be a methyl, ethyl, isopropyl or benzyl ester.
• esters of methanoproline can be prepared by conventional procedures.
• Conversion of the starting ester to the ester of 2-carboxy-3-azabicyclo(3.1.0)hex-2-ene can be carried out directly using an oxidizing agent.
• Manganese dioxide is a suitable reagent, and the oxidation can be performed simply by stirring the starting ester with manganese dioxide in the presence of a suitable solvent, for example, a hydrocarbon such as benzene or a light petroleum fraction. The reaction is conveniently performed at room temperature.
• the conversion may be carried out indirectly, for example, by chlorinating or brominating the starting ester to give the N-chloro or N-bromo ester, and dehydrohalogenating the N-halo ester.
• the halogenation may be carried out using any suitable halogenating agent, for example, N-bromo- or, especially, N-chlorosuccinimide, or an organic or inorganic hypohalite, for example, t-butyl hypochlorite or sodium hypochlorite.
• Sodium hypochlorite may conveniently be used in the form of sodium hydroxide plus chlorine.
• the halogenation is suitably carried out by admixing the halogenating agent with the starting ester.
• the reaction may, for example, be carried out at a temperature in the range of from -10° C. to +30° C., the optimum temperature depending on the halogenating agent used.
• a hypohalite is used as halogenating agent
• the reaction is preferably carried out at a temperature in the range of from -10° C. to +5° C.
• N-chlorosuccinimide is used as halogenating agent, the reaction is most conveniently carried out at room temperature.
• Suitable dehydrohalogenating agents for the dehydrohalogenation step include organic bases and inorganic bases, for example, an alkali metal hydroxide or alkoxide. Care should be taken, however, to ensure tht the reaction conditions are such that the ester group is not attacked. For this reason, the base used should be relatively non-nucleophilic; for example, sodium ethoxide is generally preferred to sodium hydroxide.
• the reaction may be carried out in any suitable polar solvent, for example, an ether or an alcohol, and is preferably carried out at a temperature of up to 150° C., preferably at a temperature in the range 0° to 80° C.
• the resulting azabicyclohexene ester may be isolated by any suitable method, or at least part of the reaction mixture containing the azabicyclohexene derivative may be used directly in the subsequent hydrogenation step.
• the hydrogenation step of the process according to the invention may, for example, be carried out by using a hydride transfer agent.
• a hydride transfer agent Preferably, however, it is carried out using gaseous hydrogen in the presence of a homogeneous or, preferably, heterogeneous catalyst, for example, a palladium or platinum catalyst, such as palladium charcoal or, preferably, pre-reduced platinum oxide.
• a homogeneous or, preferably, heterogeneous catalyst for example, a palladium or platinum catalyst, such as palladium charcoal or, preferably, pre-reduced platinum oxide.
• the process may be carried out at atmospheric pressure but it is preferably carried out at elevated pressure, for example, up to 150 atmospheres gauge.
• the hydrogenation reaction is preferably carried out at room temperature. It may, however if desired, be carried out at elevated temperature, for example, up to 100° C.
• the hydrogenation reaction is preferably carried out using this alcohol as solvent.
• an ethyl ester is used as starting material and the hydrogenation is carried out using ethanol as solvent.
• any other suitable solvent may be used if desired--for example, an ester, such as ethyl acetate, or an aromatic hydrocarbon, such as toluene. If the ester starting material is itself a liquid, the reaction may be carried out without the use of a solvent.
• the product obtained directly from the hydrogenation process if it is an ester, can be converted into methanoproline or a salt thereof.
• This may be performed by any suitable method, for example, hydrolysis under acidic or basic conditions, and if desired subsequent conversion of the resulting free acid into a salt thereof, or conversion of a resulting salt into the corresponding free acid.
• Hydrogenation of certain esters may produce the cis methanoproline directly, if the starting ester moiety is one which is cleaved by hydrogenolysis.
• a preferred embodiment of the process comprises starting from such an ester, preferably the benzyl ester.
• Example 1 The procedure of Example 1 was repeated, except that 2-isopropoxycarbonyl-3-azabicyclo(3.1.0)hexane (92% trans isomer, 8% cis isomer) was used as starting material in step (a); potassium hydroxide dissolved in isopropyl alcohol was used as dehydrohalogenating agent in step (b); and a 5% palladium charcoal catalyst in isopropyl alcohol was used in step (c).
• the resulting product was 2-isopropoxycarbonyl-3-azabicyclo(3.1.0)hexane which was shown by NMR spectrum analysis to contain 85% cis isomer, 15% trans isomer.
• step (b) was 2-isopropoxy-3-azabicyclo(3.1.0)hex-2-ene, a liquid, b.p. (0.4 Torr.): 64°-66° C. Its identity was confirmed by NMR and IR spectral analyses.
• Example 1 The procedure of Example 1 was repeated, except that the procedure of steps (a) and (b) combined were replaced by the following.
• a solution of sodium isopropoxide (prepared by dissolving 1.15 g of sodium in 100 ml of dry isopropyl alcohol) and 100 ml of dry dichloromethane, was added dropwise at 0° C. under nitrogen, in the dark. The suspension was stirred at 0° C. for 1 hour, concentrated by evaporation and the residue was treated with 100 ml of water and 500 ml of diethyl ether. The ether solution was then dried over sodium sulfate, and the solvent was evaporated. 5.9 g of an orange liquid was obtained. This was distilled under vacuum under a nitrogen atmosphere. 2.7 g of 2-isopropoxycarbonyl-3-azabicyclo(3.1.0)hex-2-ene was obtained.
• this compound was prepared from 2-methoxycarbonyl-3-azabicyclo(3.1.0)hexane. Sodium dissolved in methanol instead of ethanol was used as dehydrohalogenating agent. The desired compound was obtained as a straw-colored liquid in 70% yield. Its identity was confirmed by elemental analysis, and by NMR and IR analyses.
• esters of 2-carboxy-3-azabicyclo(3.1.0)hex-2-ene significantly inhibit the formation of pollen in cereal grain plants.
• the active esters are those wherein the ester moiety is unsubstituted alkyl or alkenyl of up to seven carbon atoms, or is benzyl.
• the ester moiety is alkyl of one to four carbon atoms.
• This invention accordingly includes the use of such esters for suppressing formation of pollen in cereal grain plants, and compositions adapted for that purpose containing the esters.
• the esters inhibit (suppress) pollen formation, apparently by sterilizing the male anthers of small-grain cereal plants, without substantially affecting female fertility. This makes it possible to produce F 1 hybrids of self-pollinating plants using a simple chemical treatment.
• the invention therefore provides a pollen-inhibiting (suppressing) composition which comprises an ester of the acid of the formula I together with a suitable carrier.
• the invention further provides a method of inhibiting (suppressing) pollen formation in a small-grain cereal plant, which comprises applying to the plant ester of 2-carboxy-3-azabicyclo(3.1.0)hex-2-ene, or a pollen-suppressing composition containing such an ester.
• the invention also provides a method of producing an F 1 hybrid seed which comprises cross-pollinating a plant which has been treated by the sterilizing process according to the invention with a second plant of a different strain.
• the active compound or composition is applied to a smal-grain cereal plant, for example, wheat or barley, when the plant is at a stage of growth between late tillering and emergence of the ear.
• the compound or composition is suitably applied at a dosage of active compound of from 0.05 to 2 kilograms per hectare, preferably at a dosage of from 0.25 to 1 kilogram per hectare.
• a carrier in a composition according to the invention is any material with which the active ingredient is formulated to facilitate application to the plant to be treated, or to facilitate storage, transport or handling.
• a carrier may be a solid or a liquid, including a material which is normally gaseous but which has been compressed to form a liquid, and any of the carriers normally used in formulating herbicidal compositions may be used.
• Suitable solid carriers include natural and synthetic clays and silicates, for example natural silicas such as diatomaceous earths; magnesium silicates, for example talcs; magnesium aluminium silicates, for example attapulgites and vermiculites; aluminium silicates, for example kaolinites, montmorillonites and micas; calcium carbonate; calcium sulphate; synthetic hydrated silicon oxides and synthetic calcium or aluminium silicates; elements, for example carbon and sulphur; natural and synthetic resins, for example coumarone resins, polyvinyl chloride, and styrene polymers and copolymers; solid polychlorophenols; bitumen; waxes, for example beeswax, paraffin wax, and chlorinated mineral waxes; and solid fertilisers, for example superphosphates.
• natural silicas such as diatomaceous earths
• magnesium silicates for example talcs
• magnesium aluminium silicates for example attapulgites and vermiculites
• Suitable liquid carriers include water; alcohols, for example isopropanol and glycols; ketones, for example acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethers; aromatic or araliphatic hydrocarbons, for example benzene, toluene and xylene; petroleum fractions, for example kerosine and light mineral oils; chlorinated hydrocarbons, for example carbon tetrachloride, perchloroethylene and trichloroethane. Mixtures of different liquids are often suitable.
• compositions are often formulated and transported in a concentrated form which is subsequently diluted by the user before application.
• a carrier which is a surface-active agent facilitates this process of dilution.
• at least one carrier in a composition according to the invention is a surface-active agent.
• the composition may contain at least two carriers, at least one of which is a surface-active agent.
• a surface-active agent may be an emulsifying agent, a dispersing agent or a wetting agent; it may be nonionic or ionic.
• suitable surface-active agents include the sodium or calcium salts of polyacrylic acids and lignin sulphonic acids; the condensation products of fatty acids or aliphatic amines or amides containing at least 12 carbon atoms in the molecule with ethylene oxide and/or propylene oxide; fatty acid esters of glycerol, sorbitan, sucrose or pentaerythritol; condensates of these with ethylene oxide and/or propylene oxide; condensation products of fatty alcohol or alkyl phenols, for example p-octylphenol or p-octylcresol, with ethylene oxide and/or propylene oxide; sulphates or sulphonates of these condensation products; alkali or alkaline earth metal salts, preferably sodium salts, of sulphuric or sulphonic
• compositions of the invention may for example be formulated as wettable powders, dusts, granules, solutions, emulsifiable concentrates, emulsions, suspension concentrates and aerosols.
• Wettable powders usually contain 25, 50 and 75% w of active ingredient and usually contain, in addition to solid inert carrier, 3-10% w of a dispersing agent and, where necessary, 0-10% w of stabiliser(s) and/or other additives such as penetrants or stickers.
• Dusts are usually formulated as a dust concentrate having a similar compositions to that of a wettable powder but without a dispersant, and are diluted in the field with further solid carrier to give a composition usually containing 1/2-10% w of active ingredient.
• Granules are usually prepared to have a size between 10 and 100 BS mesh (1.676-0.152 mm), and may be manufactured by agglomeration or impregnation techniques. Generally, granules will contain 1/2-25% w active ingredient and 0-10% w of additives such as stabilisers, slow release modifiers and binding agents. Emulsifiable concentrates usually contain, in addition to a solvent and, when necessary, co-solvent, 10-50% w/v active ingredient, 2-20% w/v emulsifiers and 0-20% w/v of other additives such as stabilisers, penetrants and corrosion inhibitors.
• additives such as stabilisers, penetrants and corrosion inhibitors.
• Suspension concentrates are usually compounded so as to obtain a stable, non-sedimenting flowable product and usually contain 10-75% w active ingredient, 0.5-15% w of dispersing agents, 0.1-10% w of suspending agents such as protective colloids and thixotropic agents, 0-10% w of other additives such as defoamers, corrosion inhibitors, stabilisers, penetrants and stickers, and water or an organic liquid in which the active ingredient is substantially insoluble; certain organic solids or inorganic salts may be present dissolved in the formulation to assist in preventing sedimentation or as anti-freeze agents for water.
• Aqueous dispersions and emulsions for example compositions obtained by diluting a wettable powder or a concentrate according to the invention with water, also lie within the scope of the present invention.
• the said emulsions may be of the water-in-oil or of the oil-in-water type, and may have a thick ⁇ mayonnaise ⁇ -like consistency.
• compositions of the invention may also contain other ingredients, for example, other compounds possessing insecticidal, herbicidal or fungicidal properties.
• esters of the invention were ascertained as follows:
• the compound to be tested was formulated as an aqueous solution containing 0.1% Nonidet P 40 as wetting agent and 1% acetone to aid solubility. This formulation was diluted with water to various concentrations and sprayed onto plants to run-off. The plants were treated at the growth stage when the second node of the plant was just detectable.

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• Life Sciences & Earth Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical & Material Sciences (AREA)
• Dentistry (AREA)
• Health & Medical Sciences (AREA)
• Engineering & Computer Science (AREA)
• Plant Pathology (AREA)
• General Health & Medical Sciences (AREA)
• Wood Science & Technology (AREA)
• Zoology (AREA)
• Environmental Sciences (AREA)
• Pest Control & Pesticides (AREA)
• Agronomy & Crop Science (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Indole Compounds (AREA)

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Citations (2)

• 1979
  • 1979-11-23 CA CA000339418A patent/CA1116617A/fr not_active Expired
  • 1979-12-03 EP EP79200714A patent/EP0012471B1/fr not_active Expired
  • 1979-12-03 DE DE7979200714T patent/DE2963826D1/de not_active Expired
  • 1979-12-07 US US06/101,992 patent/US4249936A/en not_active Expired - Lifetime
  • 1979-12-10 OA OA56970A patent/OA06406A/fr unknown
  • 1979-12-12 AR AR279255A patent/AR223504A1/es active
  • 1979-12-12 GR GR60733A patent/GR74020B/el unknown
  • 1979-12-12 PL PL22034979A patent/PL220349A1/xx unknown
  • 1979-12-12 TR TR20627A patent/TR20627A/xx unknown
  • 1979-12-12 BR BR7908140A patent/BR7908140A/pt unknown
  • 1979-12-12 IL IL58938A patent/IL58938A0/xx unknown
  • 1979-12-12 DK DK529779A patent/DK529779A/da unknown
  • 1979-12-12 DD DD79217593A patent/DD147905A5/de unknown
  • 1979-12-12 AU AU53728/79A patent/AU533729B2/en not_active Ceased
  • 1979-12-12 PT PT70576A patent/PT70576A/pt unknown

Patent Citations (2)

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